One of the biggest factors for any flight simulation add-on is performance, and so most of the major add-on developers are building C++ modules (compiled to WASM) to eek out as much performance as possible. My understanding is that it's also possible to write some things in JavaScript (and perhaps TypeScript), but performance takes a hit. I would assume Lua falls into that same performance trap, as I know Lua can be used for X-Plane add-on development, but it's (again) considered the less performance-centric approach as compared to C++.

I recall at least one add-on developer for X-Plane (Zibo [1]) migrating some of their Lua code over to C++.

[1] https://forums.x-plane.org/forums/topic/138974-b737-800x-zib...